Featured Research

Functional MRI scans have revealed a "biologically embedded" basis for altruistic behavior, with several characteristic regions of the brain being activated when players of a game called "Prisoner's Dilemma" decide to trust each other and cooperate, rather than betray each other for immediate gain, say researchers from Emory University. They report on their study in the July 18 issue of the journal Neuron, published by Cell Press.

Share This

Functional MRI scans have revealed a "biologically embedded" basis for altruistic behavior, with several characteristic regions of the brain being activated when players of a game called "Prisoner's Dilemma" decide to trust each other and cooperate, rather than betray each other for immediate gain, say researchers from Emory University. They report on their study in the July 18 issue of the journal Neuron, published by Cell Press.

Related Articles

For many years, evolutionary biologists, behaviorists, economists and political scientists have attempted to understand why cooperation exists between human beings, even though that cooperation may not result in a direct or immediate reward. This unselfish behavior called "altruism" is almost uniquely a human trait.

Up until now, almost all brain imaging experiments that have studied the social brain have done so by exposing subjects to static 2-D images inside the scanner. "This study represents an attempt to learn about the social brain by scanning people as they are engaged in a true social interaction," said James K. Rilling, Ph.D., principal investigator in the Emory study, who is currently serving a postdoctoral fellowship at Princeton University. In the Fall of 2003, Dr. Rilling will return to Emory as a faculty member with a joint appointment in the Center for Behavioral Neuroscience (CBN) at Emory University School of Medicine and the Emory University Department of Anthroplogy.

In two separate experiments, the researchers used fMRI to scan the brains of 36 women while they played the "Prisoner's Dilemma Game," a decades-old model for cooperation based on reciprocal altruism. Two players independently chose to either cooperate with each other or not (defect), and each was awarded a sum of money that depended upon the interaction of both players' choices in that round.

In the first experiment, 19 subjects were scanned in four game sessions designed to observe neural function during cooperation and non-cooperation during both human interactions (social) and interactions with a computer (non-social). The results of the first experiment revealed different patterns of neural activation depending on whether the playing partner was identified as a human or a computer. In the second experiment, 17 subjects were scanned during three game sessions, focusing specifically on human interaction.

Mutual cooperation was the most common outcome in games played with presumed human partners in both experiments, even though a player was maximally rewarded for defecting when the other player cooperated. During the mutually cooperative social interactions, activation was noted in those areas of the brain that are linked to reward processing: the nucleus accumbens, the caudate nucleus, ventromedial frontal/orbitofrontal cortex and rostral anterior cingulate cortex.

"Our study shows, for the first time, that social cooperation is intrinsically rewarding to the human brain, even in the face of pressures to the contrary, " said Gregory S. Berns, M.D., Ph.D., co-investigator and associate professor of psychiatry in the Emory University School of Medicine Department of Psychiatry and Behavioral Sciences and member of the CBN. "It suggests that the altruistic drive to cooperate is biologically embedded-- either genetically programmed or acquired through socialization during childhood and adolescence."

"Reciprocal altruism activates a reward circuit, and this activation may often be sufficiently reinforcing to override subsequent temptations to accept but not reciprocate altruism. This may be what motivates us to persist with cooperative social interactions and reap the benefits of sustained mutual cooperation," said Dr. Rilling.

"The combination of game behavior and functional brain imaging also provides a unique paradigm to explore the neural basis of social behavioral disorders such as autism, drug addiction and sociopathy, that are characterized by deficits in social reciprocity, impulse regulation, or social reward processing," adds Clint Kilts, Ph.D., co-investigator and associate professor of psychiatry at Emory. "It defines the most complex form of the human genesis of a social bond. It may help us define why wars are fought and loves are lost."

The study was sponsored by the Markey Center for Neurological Sciences Fellowship, National Institute on Drug Abuse (NIDA), National Institutes of Mental Health (NIMH) and National Alliance for Research on Schizophrenia and Depression (NARSAD). Other Emory researchers involved in the study were David A. Gutman, Thorsten R. Zeh, and Giuseppe Pagnoni, Ph.D.

More From ScienceDaily

More Mind & Brain News

Featured Research

Mar. 3, 2015 — No significant change in home habits of smokers have been observed in the aftermath of a ban on smoking in public spaces, researchers report. Greater inspiration to kick the habit likely comes from ... full story

Mar. 3, 2015 — Heart function has been associated with the development of dementia and Alzheimer's disease through a new study. Participants with decreased heart function, measured by cardiac index, were two to ... full story

Mar. 3, 2015 — Children of recently separated or divorced families are likelier to drink sugar-sweetened beverages than children in families where the parents are married, putting them at higher risk for obesity ... full story

Mar. 3, 2015 — Although sedatives are often administered before surgery, a randomized trial finds that among patients undergoing elective surgery under general anesthesia, receiving the sedative lorazepam before ... full story

Mar. 3, 2015 — Why do people shake hands? A new study suggests one of the reasons for this ancient custom may be to check out each other's odors. Even if we are not consciously aware of this, handshaking may ... full story

Mar. 3, 2015 — It appears that stress markers in unemployed people can be found, independent of smoking, alcohol consumption and overweight/obesity. Results from a study suggest that long-term unemployment may be ... full story

Mar. 3, 2015 — On the heels of an American nationwide measles outbreak comes a report that campaigns aimed at scaring people about the consequences of non-vaccination might not be as effective as many think. ... full story

Mar. 3, 2015 — Doctors write millions of prescriptions a year for drugs to calm the behavior of people with Alzheimer’s disease and other types of dementia. But non-drug approaches actually work better, and carry ... full story

Mar. 3, 2015 — Briefly counseling college students on the dangers of binge drinking is effective in lowering heavy drinking levels among many students, but only temporarily. Three out of four will be right back ... full story

Mar. 3, 2015 — Loneliness brought about by the death of a spouse can trigger a wider network of depression-like symptoms, a study has found, but authors suggest that doctors are often too quick to attribute these ... full story

Related Stories

Nov. 24, 2014 — With a new analysis of the Prisoner's Dilemma played in a large, evolving population, scientists found that adding more flexibility to the game can allow selfish strategies to be more ... full story

Nov. 13, 2014 — Research has shown that when two individuals meet repeatedly they are more likely to cooperate with one another. New research show that the most successful strategy for cooperation occurs only after ... full story

May 29, 2014 — When we must choose between cooperating with others or betraying them, we are more likely to cooperate if they have acted like this with us or if we ourselves have behaved altruistically. We do so ... full story

May 7, 2014 — People cooperate with each other more when they’ve been holding hot, as opposed to cold, objects. This is the finding of a new study. The Iterated Prisoner’s Dilemma (IPD) task, designed to ... full story

Dec. 7, 2010 — When two individuals face off in conflict, the classic problem in evolutionary biology known as the prisoner's dilemma says that the individuals are not likely to cooperate even if it is in ... full story

ScienceDaily features breaking news and videos about the latest discoveries in health, technology, the environment, and more -- from major news services and leading universities, scientific journals, and research organizations.